Coil winding tensioners · Maximum winding tension by wire size, stretch and resistance, mechanical versus closed-loop control
A wire tensioner for coil winding sits between the wire spool and the winding machine and holds the magnet wire at a set tension so that turns lie tight without stretching the conductor. Ask three things first: what maximum tension the wire maker allows for your diameter, whether the tensioner can hold a low, steady tension at your wire speed and through stops and starts, and whether it controls tension in a closed loop or only by springs and brakes.
Mechanical, magnetic (hysteresis) and servo tensioners and feeders for winding enamelled copper and aluminium wire into transformer, motor and other coils. Web and strip tension controls, cable-pulling tensioners and fence-wire tighteners are outside this page.
CNFX editorial research · Sources checked October 11, 2026 · 4 sources
Elektrisola's technical data for enamelled copper wire to IEC 60317 lists a maximum winding tension for each nominal diameter, for example 23.2 cN at 0.050 mm, 75 cN at 0.100 mm, 247 cN at 0.200 mm and 1,287 cN at 0.500 mm. [1] MWS Wire Industries publishes minimum and maximum winding tensions by AWG for copper and aluminium magnet wire — for copper, 270–360 g at 30 AWG and 25–35 g at 40 AWG; for 10 AWG, 28–37 kg — and states that its maxima are based on the yield strength of fully annealed copper, that higher tension may raise resistance, and that users should validate that wire is not stretched. [2]
MWS lists aluminium maxima at roughly a quarter of copper's for the same gauge, for example 99 g against 360 g at 30 AWG. [2]
Editorial calculation: 360 g-force is about 3.53 N or 353 cN. Using the AWG formula d = 0.127 × 92^((36 − n)/39) mm, 30 AWG is about 0.255 mm, close to Elektrisola's 0.250 mm line at 366 cN — the two makers agree there. At 40 AWG (about 0.080 mm), MWS's 35 g (about 34 cN) is well below Elektrisola's 52 cN for 0.080 mm, so take the limit from your own wire supplier. [2][1]
Give the supplier the wire material, grade and diameter range, the wire maker's maximum winding tension, target tension and tolerance, maximum wire speed and acceleration, number of spindles, coil geometry (round, rectangular), stages needing different tensions (wrapping, winding, loading), machine interface, and supply voltage or air.
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Choose open-loop or closed-loop control
A BTSR International patent on positive wire feeders states that normal winding tension ranges from 5 to 4,000 cN depending on wire diameter, and that "the smaller the wire diameter the lower is the working tension, and the greater the importance of controlling the tension during the winding stage." It explains that tension keeps turns tight to the support, including at the corners of square coils, but can also elongate the wire, reducing its cross-section and changing the coil's resistance and impedance. [3]
The patent describes fully mechanical feeders with a felt-pad brake and spring-loaded arm as open-loop systems that cannot correct changes in inlet tension, spring damage or dirt in the brake, and that allow only one set tension, whereas a closed-loop feeder can measure and correct tension and apply different values for the wrapping, winding and loading stages. [3] The linked supplier lists magnetic tensioners and servo tensioners for coil winding. [4]
Editorial calculation: because resistance scales with length divided by cross-section, and stretching keeps volume roughly constant, 1% elongation raises a wire segment's resistance by about 1.01² − 1 ≈ 2%. This is a simplified estimate that ignores work hardening. [3][2]
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Magnetic and servo tensioner series in the reviewed listing
The listing reviewed offers seven magnetic tensioner series (NMTC, MTQM, MTQ, MTAL, MTA, MTC, MTCSS) and SF1, SF2 and SETC servo tensioners [4], with ceramic guides, hysteresis brakes and tension meters; ask for each model's tension range, wire diameter range and maximum wire speed.
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From felt-pad entry brake to stage controller
The tension sensor and controller rows apply to closed-loop feeders; the BTSR patent describes the spring-and-felt mechanical type as open loop, without them.
Tension window, wire speed and guide material per model
Only the diameter, tension-range and guide-material rows carry sourced content; accuracy, speed, ambient and electrical rows need the supplier's own figures for each model.
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Compiled and source-reviewed by the CNFX editorial team.
Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review
· Page last updated 13 October 2026
Buyer questions
What tension should I wind 0.1 mm copper wire at?
Elektrisola lists a maximum winding tension of 75 cN for 0.100 mm enamelled copper wire. [1]
What happens if winding tension is too high?
MWS says tension above its maxima may raise resistance; BTSR notes elongation reduces cross-section and changes resistance. [2][3]
What tension range do winding tensioners cover?
A BTSR patent gives 5 to 4,000 cN, lower for finer wire. [3]
Why use a servo tensioner instead of a spring tensioner?
BTSR describes spring-and-brake feeders as open loop with one set tension; closed-loop feeders correct errors and set stage tensions. [3]
Sources and what still needs a direct check
Sources checked 2026-10-11. Elektrisola and MWS are magnet wire makers publishing tension limits for their wire; the BTSR patent describes tension control in winding; Zhengtaifeng is the linked supplier. Wire makers' limits differ, so use your own supplier's values.
